GLOBALNAVIGATION SATELLITE SYSTEM GLONASS TION CENTER INTERFACE CONTROL DOCUMENT COORDINATION SCIENTIFIC INFORMA MOSCOW 1998ã. Version 4.0 1998 GLONASS ICD COORDINATION SCIENTIFIC INFORMATION CENTER TABLE OF CONTENTS FIGURES................................................................................................................................................................... 2 TABLES .................................................................................................................................................................... 3 ABBREVIATIONS.................................................................................................................................................... 4 1. INTRODUCTION ................................................................................................................................................. 5 1.1 GLONASS PURPOSE.......................................................................................................................................... 5 1.2 GLONASS COMPONENTS .................................................................................................................................. 5 1.3 NAVIGATION DETERMINATION CONCEPT ............................................................................................................. 5 2. GENERAL............................................................................................................................................................. 6 2.1 ICD DEFINITION ................................................................................................................................................ 6 2.2 ICD APPROVAL AND REVISION............................................................................................................................ 6 3. REQUIREMENTS ................................................................................................................................................ 7 3.1 INTERFACE DEFINITION ...................................................................................................................................... 7 3.2 NAVIGATION SIGNAL STRUCTURE ....................................................................................................................... 8 3.2.1 Ranging code............................................................................................................................................. 8 3.2.2 Digital data of navigation message ............................................................................................................ 8 3.3 INTERFACE DESCRIPTION.................................................................................................................................... 8 3.3.1 Navigation RF signal characteristics.......................................................................................................... 8 3.3.1.1 Frequency plan................................................................................................................................... 8 3.3.1.2 Correlation loss ................................................................................................................................ 10 3.3.1.3 Carrier phase noise........................................................................................................................... 10 3.3.1.4 Spurious emissions........................................................................................................................... 10 3.3.1.5 Intrasystem interference.................................................................................................................... 10 3.3.1.6 Received power level........................................................................................................................ 10 3.3.1.7 Equipment group delay..................................................................................................................... 11 3.3.1.8 Signal coherence .............................................................................................................................. 11 3.3.1.9 Polarization ...................................................................................................................................... 11 3.3.2 Modulation.............................................................................................................................................. 11 3.3.2.1 Ranging code generation .................................................................................................................. 11 3.3.2.2 Navigation message generation......................................................................................................... 13 3.3.3 GLONASS time ........................................................................................................................................ 15 3.3.4 Coordinate system ................................................................................................................................... 16 4. NAVIGATION MESSAGE................................................................................................................................. 17 4.1 NAVIGATION MESSAGE PURPOSE....................................................................................................................... 17 4.2 NAVIGATION MESSAGE CONTENT...................................................................................................................... 17 4.3 NAVIGATION MESSAGE STRUCTURE .................................................................................................................. 17 4.3.1 Superframe structure ............................................................................................................................... 17 4.3.2 Frame structure....................................................................................................................................... 19 4.3.3 String structure........................................................................................................................................ 21 4.4 IMMEDIATE INFORMATION AND EPHEMERIS PARAMETERS .................................................................................. 21 4.5 NON-IMMEDIATE INFORMATION AND ALMANAC ................................................................................................ 26 4.6 RESERVED BITS................................................................................................................................................ 29 4.7 DATA VERIFICATION ALGORITHM ..................................................................................................................... 30 5. GLONASS SPACE SEGMENT .......................................................................................................................... 32 5.1 CONSTELLATION STRUCTURE ........................................................................................................................... 32 5.2 ORBITAL PARAMETERS..................................................................................................................................... 32 5.3 INTEGRITY MONITORING .................................................................................................................................. 33 APPENDIX 1........................................................................................................................................................... 35 APPENDIX 2........................................................................................................................................................... 36 APPENDIX 3........................................................................................................................................................... 37 1 Version 4.0 1998 GLONASS ICD COORDINATION SCIENTIFIC INFORMATION CENTER FIGURES page Fig. 3.1 Satellite/Receiver Interface 7 Fig. 3.2 Structure of shift register used for ranging code generation 12 Fig. 3.3 Simplified block diagram of PR ranging code and clock pulse generation 12 Fig. 3.4 Simplified block diagram of data sequence generation 13 Fig. 3.5 Time relationship between clock pulses and PR ranging code 14 Fig. 3.6 Data sequence generation in onboard processor 14 Fig. 4.1 Superframe structure 18 Fig. 4.2 Frame structure 20 Fig. 4.3 String structure 21 Fig. A.1 Relationship between minimum received power level and angle of elevation 35 2 Version 4.0 1998 GLONASS ICD COORDINATION SCIENTIFIC INFORMATION CENTER TABLES page Table 3.1 GLONASS carrier frequencies in L1 and L2 sub-bands 9 Table 3.2 Geodetic constants and parameters of PZ-90 common terrestrial ellipsoid 16 Table 4.1 Arrangement of GLONASS almanac within superframe 19 Table 4.2 Accuracy of determination of coordinates and velocity for GLONASS satellite 22 Table 4.3 Word P1 22 Table 4.4 Word FT 23 Table 4.5 Characteristics of words of immediate information (ephemeris parameters) 24 Table 4.6 Arrangement of immediate information within frame 25 Table 4.7 Word KP 27 Table 4.8 Relationship between "age" of almanac and accuracy of positioning 27 Table 4.9 Characteristics of words of non-immediate information (almanac) 28 Table 4.10 Negative numbers of GLONASS carriers within navigation message 28 Table 4.11 Arrangement of non-immediate information within frame 29 Table 4.12 Arrangement of reserved bits within superframe 29 Table 4.13 Algorithm for verification of data within string